Powder layer composite, coating film, powder coating method, and powder coating apparatus

ABSTRACT

A powder layer composite includes a base and a powder layer having a thickness of 100 μm or less and disposed on the base. An average of a total value of a number of powder aggregates having a long diameter of 500 μm or greater and a number of pinholes having a long diameter of 500 μm or greater, in any of a plurality of different regions of 20 mm×20 mm on a surface of the powder layer, is 0.2 pieces/cm 2  or less.

BACKGROUND 1. Technical Field

The present disclosure relates to a powder layer composite, a coatingfilm, a powder coating method, and a powder coating apparatus.

2. Description of the Related Art

In powder coating, since a base can be coated with a powder coatingmaterial, it is not necessary to prepare a liquid coating material usinga solvent, which is useful as an environmentally friendly coatingmethod. When a powder having a relatively large particle size, that is,having an average particle size of 10 μm or greater is used, a coatingfilm having a thickness of 50 μm or greater can be formed by one coatingwithout the trouble of recoating. However, when a highly cohesivecoating material is used, a step of disassembling an aggregated particleby giving kinetic energy by stirring or the like may be required.

For example, Japanese Patent Unexamined Publication No.

2001-170551 describes a method of transporting powder from a gas blowingtype fluid bed type powder tank to an ejection gun, that is, a methodfor transporting a trace amount of powder in which the powder particlespresent in a suspended state, that is, as the powder aerosol, are suckedand transported above a level surface of a powder fluid bed in thepowder tank.

SUMMARY

According to an aspect of the present disclosure, there is provided apowder layer composite including a base and a powder layer having athickness of 100 μm or less and disposed on the base. An average of atotal value of a number of powder aggregates having a long diameter of500 μm or greater and a number of pinholes having a long diameter of 500μm or greater, in any of a plurality of different regions of 20 mm×20 mmon a surface of the powder layer, is 0.2 pieces/cm² or less.

According to another aspect of the present disclosure, there is provideda coating film, in which the coating film has a thickness of 100 μm orless, the coating film is provided on a base, and the coating film has asurface roughness Ra of 5.0 μm or less.

According to still another aspect of the present disclosure, there isprovided a powder coating apparatus including: a powder disperser thatdisperses powder; and a powder supplier that is connected to the powderdisperser and supplies the dispersed powder directly onto a base withoutstoring the powder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory view illustrating a configuration example of apowder layer composite according to an exemplary embodiment of thedisclosure;

FIG. 2 is a schematic view of a powder coating apparatus according tothe exemplary embodiment of the disclosure;

FIG. 3 is a schematic view of the powder coating apparatus used in anexample of the disclosure;

FIG. 4 is a view illustrating a 1000 times SEM image of a coating filmof Comparative Example 1 and a 10000 times SEM image of the coating filmof Comparative Example 1;

FIG. 5 is a graph illustrating arithmetic average roughness Ra of thecoating film surface when the coating film of Examples 1 and 2 andComparative Example 2 is magnified 10 times, 20 times, 50 times, and 150times;

FIG. 6 is a view illustrating a three-dimensional surface image of thecoating film of Examples 1 and 2 and Comparative Example 2 magnified 150times;

FIG. 7 is a view illustrating a 20 times SEM image of the coating filmof Example 2 and Comparative Example 2;

FIG. 8A is a view illustrating an original profile of EDX of Example 2;

FIG. 8B is a view illustrating an original profile of EDX of ComparativeExample 2;

FIG. 8C is a view illustrating a correction profile of Example 2;

FIG. 8D is a view illustrating a correction profile of ComparativeExample 2;

FIG. 9 illustrates Table 1 listing conditions for spraying a powdercoating material toward a metal mask; and

FIG. 10 illustrates Table 2 listing measurement results of Examples andComparative Examples.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

When fine particles having an average particle size of 10 μm or less areused as a powder coating material, the cohesiveness of powder is high,and it is difficult to sufficiently perform high-order dispersion by themethod of Japanese Patent Unexamined Publication No. 2001-170551.Specifically, it is not easy to form a uniform thin film having athickness of 100 μm or less with high quality. There is a concern thatcoating defects such as powder clogging in the coating apparatus due topowder aggregates occur.

An object of the present disclosure is to provide a powder layercomposite, a coating film, a powder coating method, and a powder coatingapparatus capable of forming a high-quality coating film even whenpowder having fine particles is used.

The powder layer composite according to an aspect of the disclosureincludes a base and a powder layer having a thickness of 100 μm or lessand disposed on the base. An average of a total value of a number ofpowder aggregates having a long diameter of 500 μm or greater and anumber of pinholes having a long diameter of 500 μm or greater, in anyof a plurality of different regions of 20 mm×20 mm on a surface of thepowder layer, is 0.2 pieces/cm² or less. Here, the pinhole means a holeformed by the powder aggregate falling off from the powder layer.

On the surface of powder layer 5 in powder layer composite 100 accordingto the aspect of the disclosure, there are few powder aggregates andpinholes having a certain size or larger. Therefore, powder layer 5 isformed of uniformly dispersed powder. Furthermore, by heating orpressing powder layer 5, uniform coating film 51 having a small surfaceroughness can be obtained. Such high-quality coating film 51 may have anexcellent appearance and may have excellent performance when being usedas an electrode layer of, for example, a power storage device.

Powder Layer Composite and Manufacturing Process Thereof

Hereinafter, the powder layer composite of the exemplary embodiment willbe described in detail. Each of the exemplary embodiments describedbelow is a comprehensive or specific example. Numerical values, shapes,materials, configuration elements, arrangement positions and connectionforms of configuration elements, processes and the like, which areillustrated in the following exemplary embodiments, are examples, andare not intended to limit the disclosure. Among the configurationelements in the following exemplary embodiments, the configurationelements which are not described in the independent claims describingthe highest level concept will be described as any configurationelement.

FIG. 1 is an explanatory view illustrating an example of a manufacturingprocess of the powder layer composite and the coating film according toan exemplary embodiment of the disclosure. (a) of FIG. 1 illustrates aschematic cross section of base 1 coated with powder coating material 2.(b) of FIG. 1 illustrates a cross section of powder layer composite 100obtained by coating. (c) of FIG. 1 illustrates a cross section of powderlayer composite 100 a obtained by further heating or pressurizing powderlayer composite 100.

Powder layer composite 100 in (b) of FIG. 1 has a structure in whichpowder layer 5 is formed on base 1. The material, shape, and size ofbase 1 are not particularly limited, and a material capable of formingpowder layer 5 by powder coating may be used.

Powder layer 5 is formed by coating base 1 with powder coating material2 by powder coating as illustrated in (a) of FIG. 1. Powder coatingmaterial 2 is not particularly limited as long as powder coatingmaterial 2 is a non-conducting material having chargeability, but fromthe viewpoint of excellent coating efficiency, the volume resistivityvalue may be, for example, 10⁸ Ωcm or greater and 10¹⁸ Ωcm or less.Furthermore, in order to improve the coating efficiency, the volumeresistivity value may be 10¹¹ Ωcm or greater and 10¹⁴ Ωcm or less. Whenthe volume resistivity value is 10¹⁸ Ωcm or less, the electric chargescharged on powder coating material 2 do not become excessively high, andthus, the repulsion phenomenon is unlikely to occur in powder layer 5during coating. When the volume resistivity value is 10⁸ Ωcm or greater,the charge amount does not become excessively low, and the discharge ofelectric charges tends to be kept in an excellent range. Therefore,powder coating material 2 is less likely to fall off. Examples ofnon-conducting materials include: resins such as alkyd resins, acrylicresins, amino resins, epoxy resins, phenol resins, unsaturated polyesterresins, silicone resins, polyphenylene ethers, and polycarbonate; andceramics such as alumina, zirconia, barium titanate, silicon nitride,aluminum nitride, and silicon carbide.

The thickness of powder layer 5 is 100 μm or less. The average particlesize of the particles that form powder layer 5 is, for example, 10 μm orless. In other words, powder layer 5 may be formed by using powdercoating material 2 having an average particle size of particles of 10 μmor less. By using powder coating material 2 having an average particlesize of 10 μm or less, the thickness of powder layer 5 of 100 μm or lesscan be easily realized.

An average of the total value of the number of powder aggregates havinga long diameter of 500 μm or greater and pinholes having a long diameterof 500 μm or greater, in any of a plurality of different regions of 20mm×20 mm on the surface of powder layer 5, is 0.2 pieces/cm² or less. Infine particle powder coating material 2 having an average particle sizeof 10 μm or less, the adhesion between particles due to van der Wagsforce, electrostatic force, liquid cross-linking force, and the like isgenerally dominated rather than the gravity of the particles themselves,and it becomes easy to aggregate particles rapidly. Therefore, whenusing powder coating material 2 for powder coating without cracking orcrushing, powder aggregates or pinholes are likely to occur in coatingfilm 51. Coating defects such as powder clogging in the powder coatingapparatus may also occur. However, by forming powder layer 5 by thepowder coating apparatus and the powder coating method described later,powder layer 5 having few powder aggregates and pinholes can be formed.

The average of the total value of the number of powder aggregates havinga long diameter of 100 μm or greater and 500 μm or less and the numberof pinholes having a long diameter of 100 μm or greater and 500 μm orless, in any of a plurality of different regions of 4.0 mm×6.0 mm on thesurface of powder layer 5 is, for example, 10 pieces/cm² or less. Inthis case, coating film 51 obtained by heating or pressing powder layer5 can have more excellent quality. The average of the total value of thenumber of powder aggregates having a long diameter of 50 μm or greaterand 100 μm or less and the number of pinholes having a long diameter of50 μm or greater and 100 μm or less, in any of a plurality of differentregions of 0.4 mm×0.6 mm on the surface of powder layer 5 may be 10pieces/cm² or less.

The concentration of the solvent contained in powder layer 5 may be avery small amount, for example, 50 ppm or less. In other words, powderlayer 5 may be formed by using powder coating material 2 which does notsubstantially contain a solvent. By not using a solvent for the coating,it is possible to realize an environmentally friendly coating. When thefine particles are coated using a solvent, cracks and the like arelikely to occur in coating film 51 formed by heating or pressing powderlayer 5. However, when powder layer 5 is coated with powder coatingmaterial 2 which does not substantially contain a solvent, coating film51 formed of powder layer 5 is less likely to be cracked, and coatingfilm 51 having high quality can be obtained.

Coating Film 51

Coating film 51 of (c) of FIG. 1 is obtained by heating or pressingpowder layer 5 formed on base 1 of (b) of FIG. 1. The thickness ofcoating film 51 is 100 μm or less. Coating film 51 contains powderhaving an average particle size of 10 μm or less.

Surface roughness Ra of coating film 51 is 5.0 μm or less. When surfaceroughness Ra is 5.0 μm or less, coating film 51 has an excellent surfaceappearance, and coating film 51 having a uniform surface and having ahigh quality is achieved.

When the change rate is a value obtained by dividing an original profilevalue, which is obtained by measuring a signal intensity derived from acomposition of base 1 at a total of 500 points every 10 μm between anytwo points separated by 5.0 mm on the surface of coating film 51, by amoving average value of sections at ten points, a change rate is, forexample, within a range of 100±99%. The signal intensity profile ismeasured by energy dispersion type X-ray analysis (Energy DispersiveX-ray microanalysis (EDX)).

It is considered that such signal intensity is realized by having fewvoids inside coating film 51. Since there are few voids inside coatingfilm 51, base 1 is less likely to corrode, and thus, coating film 51contributes to the durability of base 1. Since there are few voidsinside coating film 51, the signal intensity derived from base 1 tendsto be uniform over the entire coating film 51. Therefore, for example,when coating film 51 is used as an electrode layer of a power storagedevice or the like, the performance of the electrode can be improved.

Powder Coating Method and Powder Coating Apparatus

A powder coating method for forming powder layer 5 and a powder coatingapparatus used for forming powder layer 5 according to the disclosurewill be described in detail. Specifically, a powder coating method and apowder coating apparatus for forming coating film 51 by powder coatingusing powder having an average particle size of 10 μm or less will bedescribed.

FIG. 2 illustrates the powder coating apparatus of the exemplaryembodiment. The powder coating apparatus, spray gun 30 having a built-inhigh-voltage corona discharge electrode, powder supplier 20, powderdisperser 10, and control device 40 are provided.

First, powder coating material 2 is supplied to powder disperser 10, andthe powder in powder coating material 2 is dispersed to remove powderaggregates. Powder disperser 10 includes, for example, atomizer 11 andcup 12. Atomizer 11 disperses the powder by, for example, crushing andatomizing the powder in cup 12 by ultrasonic vibration. Although FIG. 2illustrates an example in which powder disperser 10 includes onlyatomizer 11 and cup 12, powder disperser 10 may further include, forexample, a jet mill as a crusher, supply the powder crushed by thecrusher to cup 12, and disperse powder by atomizer 11. As the crusher,powder disperser 10 may include at least one selected from the groupconsisting of an air flow type fine crusher such as a jet mill, agrinding type fine crusher such as a roller mill, a stirring type finecrusher such as a planetary ball mill, a vibration type fine crushersuch as a vibrating ball mill, a swirling air flow type air classifiersuch as a cyclone, a centrifugal type classifier, and a vibration screentype classifier. By using these devices, powder coating material 2 canbe crushed or cracked to a predetermined size. Powder disperser 10 canremove powder aggregates by providing a classifier as needed. Therefore,the powder containing fine particles can be excellently dispersed.Powder disperser 10 may include, as cup 12, at least one of anultrasonic vibrator that ultrasonically vibrates the powder and avoltage applier that applies a high voltage to the powder. The powdercan be atomized by ultrasonically vibrating the powder or applying ahigh voltage to the powder. Accordingly, it is possible to moreexcellently disperse the powder.

Next, powder layer 5 is formed on base 1 by directly supplying thedispersed powder onto base 1 without storing the powder. In FIG. 2, thedispersed powder is directly supplied to powder supplier 20 connected topowder disperser 10. As illustrated in FIG. 2, since powder disperser 10and powder supplier 20 such as an injector are connected to each other,powder coating material 2 dispersed by powder disperser 10 can bedirectly supplied to powder supplier 20. Furthermore, as illustrated in(a) of FIG. 1, powder coating material 2 transported from powdersupplier 20 together with air in a supply hose is electrostaticallyapplied by spray gun 30 and sprayed onto base 1. Accordingly, asillustrated in (b) of FIG. 1, powder layer 5 is formed of powder coatingmaterial 2 on base 1. By heating or pressing powder layer 5 asnecessary, coating film 51 can be formed of powder coating material 2 onbase 1 as illustrated in (c) of FIG. 1.

Even when fine particles having an average particle size of 10 μm orless are dispersed by powder disperser 10 to remove powder aggregates,there is concern that the fine particles are temporarily stored in acontainer and reaggregate. However, by transporting the dispersed powderfrom powder supplier 20 to spray gun 30 without storing the powder, thepowder can be supplied onto base 1 in an air-dispersed state, that is,in an aerosol state. Therefore, powder layer 5 having few powderaggregates and pinholes can be obtained, and high-quality coating film51 can be obtained.

Powder disperser 10 may include only one of atomizer 11 and cup 12described above. Only one cup 12 may be included, or two or more cups 12may be included. Only one atomizer 11 may be included, or two or moreatomizers 11 may be included. From the viewpoint of excellentlydispersing powder coating material 2, the powder coating apparatus mayinclude two or more powder dispersers 10. Powder disperser 10 mayinclude, for example, both a fine crusher such as an air flow type finecrusher, a grinding type fine crusher, a stirring type fine crusher, anda vibration type fine crusher, and a classifier such as a swirling airflow type air classifier, a centrifugal type classifier, and a vibrationscreen type classifier. As powder disperser 10, both a fine crusher andan atomizing device such as an ultrasonic vibrator and a voltage appliermay be used. Both a classifier and an atomizing device may be provided.From the viewpoint of enhancing dispersibility, a fine crusher, aclassifier, and an atomizing device may all be provided. Powderdisperser 10 may be provided with a plurality of fine crushers, may beprovided with a plurality of classifiers, and may be provided with aplurality of atomizing devices. When powder disperser 10 includes a finecrusher, a classifier, and an atomizing device, the order of applicationto the powder is not particularly limited. For example, after crushingthe powder using a fine crusher, and further, after removing the powderaggregates using a classifier, the powder may be atomized using anatomizing device.

Powder disperser 10 may function as powder supplier 20. For example,when a fine crusher is used as powder disperser 10, powder coatingmaterial 2 dispersed directly from the fine crusher to spray gun 30 maybe supplied without going through powder supplier 20 such as aninjector.

The powder coating apparatus is not limited to the configurationillustrated in FIG. 2, and may have the configuration illustrated inFIG. 3. The powder coating apparatus of FIG. 3 is different from that ofFIG. 2 in that powder supplier 20 is deleted and powder disperser 10 isa jet mill as a crusher. The differences will be mainly described below.The powder disperser 10 of FIG. 3 schematically illustrates a horizontalcross section of a jet mill. The jet mill has mill frame 101, ceramicliner 102, pusher nozzle 103, a plurality of gliding nozzles 104,crushing zone 110, and outlet 111.

Ceramic liner 102 is fitted into mill frame 101.

The plurality of gliding nozzles 104 are provided below crushing zone110 and blow compressed air into crushing zone 110.

Pusher nozzle 103 discharges the powder into crushing zone 110. Thedischarged powder is blown into crushing zone 110 by the compressed air.The plurality of gliding nozzles 104 blow compressed air into crushingzone 110. Accordingly, the powder is crushed by swirling around crushingzone 110 and colliding with each other. The powder is classified by thecentrifugal force of the swirling motion, the fine powder is dischargedfrom outlet 111, and the coarse powder is repeatedly crushed in crushingzone 110.

The jet mill is configured to supply the dispersed powder directly fromoutlet 111 onto base 1 via spray gun 30 without storing the dispersedpowder.

Example

Examples of the present exemplary embodiment will be described below,but the disclosure is not limited to these examples.

Preparation of Powder Layer Composite 100 and Coating Film 51 Example 1

Polyacrylate particles (manufactured by Soken Kagaku Co., Ltd.,monodisperse acrylate particles, product number MP-1000, averageparticle size 0.40 μm) was used as powder coating material 2, and asheet obtained by punching electrolytic copper foil (manufactured by JXNippon Mining & Metals Co., Ltd., product number JTCSLC) into a size of70 mm×70 mm was used as base 1. The powder coating apparatus used, as anelectrostatic powder coating apparatus, the hand gun system GX8500aCStype (coating material supply device, powder spray gun GX132 typenegative ion gun, and control controller GX385a type set) manufacturedby Parker Engineering Co., Ltd, as a base. In this electrostatic powdercoating apparatus, as illustrated in FIG. 2, cup 12 for accommodatingpowder was disposed at the lower portion of the injector as powdersupplier 20, and aerosol-like powder coating material 2 atomized byatomizer 11 that applies the ultrasonic vibration from the lower portionof cup 12 was sucked into the injector. Atomizer 11 used a DGSoscillator manufactured by Artech Ultrasonic Systems of Switzerland anda C35-SD8 (corresponding to high amplitude) converter, as the ultrasonicvibrator. At the time of coating, the distance from the tip of spray gun30 to base 1 was disposed so as to be in the range of 100 to 200 mm. Theelectrolytic copper foil, which is base 1, was masked with a size of 20mm×20 mm, powder coating material 2 was sprayed onto the metal maskunder the conditions illustrated in Table 1 of FIG. 9 below, powderlayer 5 was formed on base 1, and powder layer composite 100 wasobtained. Obtained powder layer composite 100 was heated at 250° C. for1 hour to obtain coating film 51 on base 1.

Example 2

Powder disperser 10 of Example 2 includes the jet mill of FIG. 3 insteadof the configuration including the injector, the cup, and the ultrasonicvibrator of Example 1. Powder layer composite 100 and coating film 51were obtained by the same configuration and method as those in Example 1except that the jet mill was directly connected to spray gun 30. For thejet mill, the supply hose was directly connected to the spray gun usingan AO jet mill (ultra-small amount lab jet mill) manufactured by SeishinEnterprise Co., Ltd.

Example 3

Powder disperser 10 of Example 3 has a configuration in which two jetmills are connected to each other in series. Powder layer composite 100and coating film 51 were obtained by the same configuration and methodas those in Example 2 except that two jet mills were connected to eachother in series. Table 2 of FIG. 10 illustrates the characteristics ofpowder layer 5 and coating film 51.

Comparative Example 1

Using a slurry in which powder coating material 2 used in Example 1 wasdispersed in ethanol so as to be 20% by weight, guide coating wasperformed with an applicator adjusted so that the coating gap is 0.5 mm.As base 1, the same one as that in Example 1 was used. After thecoating, the slurry layer formed on base 1 was dried and heated underthe same conditions as those in Example 1 to obtain coating film 51.

Comparative Example 2

In Comparative Example 2, a powder coating apparatus in which atomizer11 of FIG. 2 is deleted and powder supplier 20 and cup 12 are arrangedupside down was used. In other words, by the same method as that inExample 1 except that the ultrasonic vibrator, which is the powderdisperser, was not used, and cup 12 was disposed not at the lowerportion but at the upper portion of the injector as the powder supplier20, powder layer composite 100 and coating film 51 were obtained.

Comparative Example 3

By the same method as that in Example 1 except that air was suppliedfrom the lower portion of the tank and powder coating material 2 in theform of a jet powder (aerosol) blown up by the air is sucked into theinjector for coating, powder layer composite 100 and coating film 51were formed. In Comparative Example 3, since the amount of aerosolizedjet powder was extremely small, the amount of spray was small and powderlayer 5 could not be formed on base 1. Therefore, the evaluation testdescribed later was not performed in Comparative Example 3.

Evaluation Test Thickness

Regarding coating film 51 obtained in Examples 1 to 3 and ComparativeExamples 1 and 2, by using a digital micrometer (MODEL MDQ-30MXmanufactured by Mitutoyo Co., Ltd.), a difference between the averagevalue of seven points excluding the maximum value and the minimum valueof the thickness data of nine points, which was measured from coatingfilm 51 having a size of 20 mm×20 mm, and the thickness of base 1, whichwas measured by the same method, was calculated and used as thethickness of coating film 51. The result is illustrated in Table 2 ofFIG. 10.

Number of Powder Aggregates and Pinholes

Regarding powder layer 5 in powder layer composite 100 obtained inExamples 1 to 3 and Comparative Example 2, the number of powderaggregates and pinholes formed by the powder aggregates falling off frompowder layer 5 was counted according to the defect size using a digitalmicroscope (VHX-900 manufactured by Keyence Co., Ltd.). When observingpowder aggregates and pinholes of 500 μm or greater, the size of thelong diameter of the abnormal portion was measured with ×10 times fieldof view of the digital microscope while focusing on the abnormal pointsthat were visually confirmed in advance in five regions of the powderlayer of 20 mm×20 mm, and the number of powder aggregates and pinholeswas counted. Similarly, for powder aggregates and pinholes having a longdiameter of 100 μm or greater and less than 500 μm, five regions of apowder layer of 4.0 mm×6.0 mm, which could be visually observed with a×10 times field of view of the digital microscope, were randomlyobserved, and the number of defects of the size was counted. For powderaggregates and pinholes having a long diameter of 50 μm or greater andless than 100 μm, five regions of a powder layer of 0.4 mm×0.6 mm, whichcould be visually observed with a ×100 times field of view, wererandomly observed, and the number of defects of the size was counted.Furthermore, in any of the measurements of the number of defects, theaverage value of the five measured values obtained by measuring once ineach of the five different regions was defined as the number of defects.The result is illustrated in Table 2 of FIG. 10. The powder aggregatesand the pinholes have a circular, elliptical or polygonal shape, or acombined shape thereof. The long diameter means the length of the linesegment connecting the two farthest points to each other in the powderaggregate and the pinhole.

In Comparative Example 1, as illustrated in FIG. 4, since cracks weregenerated in the slurry layer in the drying process, the number ofpowder aggregates and pinholes was not measured. (a) of FIG. 4 is a 1000times SEM image of coating film 51 of Comparative Example 1, and (b) ofFIG. 4 is a 10000 times SEM image.

Arithmetic Average Roughness Ra

Regarding coating film 51 obtained in Examples 1 to 3 and ComparativeExamples 1 and 2, in accordance with JIS-B0601, by using a shapemeasurement laser microscope (manufactured by KEYENCE Co., Ltd.,VK-9700), arithmetic average roughness Ra of the surface of coating film51 magnified 50 times with shape analysis application VK-H1A1 wasmeasured. The result is illustrated in Table 2 of FIG. 10.

FIG. 5 illustrates arithmetic average roughness Ra of the coating filmsurface when the coating film of Examples 1 and 2 and ComparativeExample 2 is magnified 10 times, 20 times, 50 times, and 150 times. FIG.6 is a view illustrating a three-dimensional surface image of thecoating film of Examples 1 and 2 and Comparative Example 2 magnified 150times. (a) of FIG. 6 illustrates a three-dimensional surface image ofcoating film 51 of Example 1 magnified 150 times. (b) of FIG. 6illustrates a three-dimensional surface image of coating film 51 ofExample 2 magnified 150 times. (c) of FIG. 6 illustrates athree-dimensional surface image of coating film 51 of ComparativeExample 2.

In-plane Void Distribution

Regarding coating film 51 obtained in Examples 1 to 3 and ComparativeExamples 1 and 2, by using energy dispersion type X-ray analysis (EDX:Energy Dispersive X-ray microanalysis) (3D SEM image measurementanalysis system VE-9800 manufactured by KEYENCE Co., Ltd.), the voiddistribution within the plane of coating film 51 was measured. Thesignal intensity of CuL derived from the electrolytic copper foil asbase 1 was measured at a total of 500 points every 10 μm between any twopoints separated by 5.0 mm on the surface of coating film 51 to obtainthe original profile. Table 2 of FIG. 10 illustrates the maximum valueand the minimum value of the correction profile corrected by using avalue obtained by dividing the original profile value by the movingaverage value of sections at ten points as a change rate.

FIG. 7 is a view illustrating a 20 times SEM image of the coating filmof Example 2 and Comparative Example 2. (a) of FIG. 7 illustrates an SEMimage of the surface of coating film 51 of Example 2 magnified 20 times,and (b) of FIG. 7 illustrates an SEM image of the surface of coatingfilm 51 of Comparative Example 2 magnified 20 times. Furthermore, FIGS.8A and 8B illustrate the original profile of EDX of Example 2 andComparative Example 2, respectively. FIGS. 8C and 8D illustrate thecorrection profile of Example 2 and Comparative Example 2, respectively.

As illustrated in Table 2 of FIG. 10, powder layer 5 of Examples 1 to 3has less powder aggregates and pinholes than those of powder layer 5 ofComparative Example 2. Coating film 51 of Examples 1 to 3 has a thinnerthickness and a lower surface roughness than those of ComparativeExample 2. Therefore, it is found that coating film 51 of Examples 1 to3 can achieve both thinning and high quality which are difficult to beachieved by the powder coating method of the related art.

As described above, powder layer composite 100 according to an aspect ofthe embodiment includes: base 1; and powder layer 5 having a thicknessof 100 μm or less and formed on base 1, and an average of a total valueof the number of powder aggregates having a long diameter of 500 μm orgreater and the number of pinholes having a long diameter of 500 μm orgreater, in any of a plurality of different regions of 20 mm×20 mm on asurface of powder layer 5, is 0.2 pieces/cm² or less. The average may bethe average of the five total values.

According to this, high-quality coating film 51 can be formed by heatingor pressing powder layer 5 as needed.

Here, the average of the total value of the number of powder aggregateshaving a long diameter of 100 μm or greater and 500 μm or less and thenumber of pinholes having a long diameter of 100 μm or greater and 500μm or less, in any of a plurality of different regions of 4.0 mm×6.0 mmon the surface of powder layer 5 may be 10 pieces/cm² or less. Theaverage may be the average of the five total values.

According to this, it is possible to form coating film 51 having ahigher quality with less powder aggregates and pinholes.

Here, the average of the total value of the number of powder aggregateshaving a long diameter of 50 μm or greater and 100 μm or less and thenumber of pinholes having a long diameter of 50 μm or greater and 100 μmor less, in any of a plurality of different regions of 0.4 mm×0.6 mm onthe surface of powder layer 5 may be 10 pieces/cm² or less. The averagemay be the average of the five total values.

According to this, it is possible to form coating film 51 having ahigher quality with less powder aggregates and pinholes.

Here, the concentration of the solvent contained in powder layer 5 maybe 50 ppm or less.

According to this, since the dry coating is used instead of the wetcoating, the occurrence of cracks can be suppressed and coating film 51having a higher quality can be formed.

Here, the average particle size of the particles that form powder layer5 is, for example, 10 μm or less. The average particle size is avolume-based average value obtained by the light scattering method usinglaser light based on JIS Z 8819-2: 2001.

According to this, it is possible to form coating film 51 having ahigher quality with narrow particle size.

Coating film 51 according to the aspect of the embodiment has athickness of 100 μm or less, is provided on base 1, and has surfaceroughness Ra of coating film 51 of 5.0 μm or less.

According to this, coating film 51 having a thickness of 100 μm or lesscan be made with high quality.

Here, when the change rate is a value obtained by dividing an originalprofile value, which is obtained by measuring a signal intensity derivedfrom a composition of base 1 at a total of 500 points every 10 μmbetween any two points separated by 5.0 mm on the surface of coatingfilm 51, by a moving average value of sections at ten points, a changerate may be within a range of 100±99%.

According to this, the surface roughness of coating film 51 can bereduced and the uniformity can be improved.

The powder coating method according to the aspect of the embodiment is apowder coating method for forming coating film 51 using powder having anaverage particle size of 10 μm or less, the method including: removingpowder aggregates by dispersing the powder; and forming powder layer 5on base 1 by directly supplying the dispersed powder onto base 1 withoutstoring the powder.

According to this, first, powder layer 5 can be formed, and coating film51 having a higher quality can be formed of powder layer 5.

Here, when dispersing the powder, dispersing may be performed using atleast one selected from a group consisting of an air flow type finecrusher, a grinding type fine crusher, a stirring type fine crusher, avibration type fine crusher, a swirling air flow type air classifier, acentrifugal type classifier, and a vibration screen type classifier.

According to this, various fine crushers and classifiers can be used fordispersing the powder, and the powder can be dispersed excellently.

Here, when dispersing the powder, dispersing may be performed byperforming atomization using at least one of ultrasonic vibration andhigh voltage application.

According to this, at least one of ultrasonic vibration and high voltageapplication can be used for dispersing the powder, and the powder can bedispersed excellently.

Here, in forming powder layer 5, the dispersed powder may be suppliedonto base 1 in an air-dispersed state.

According to this, since the powder is supplied onto base 1 in anair-dispersed state, that is, in an aerosol state, powder layer 5 havingfew powder aggregates and pinholes can be obtained, and coating film 51having a higher quality can be obtained.

The powder coating apparatus according to the aspect of the embodimentincludes: powder disperser 10 that disperses powder; and powder supplier20 that is connected to the powder disperser and supplies the dispersedpowder directly onto a base without storing the powder.

According to this, first, powder layer 5 can be formed, and coating film51 having a higher quality can be formed of powder layer 5.

Powder disperser 10 may include, for example, at least one of an airflow type fine crusher, a grinding type fine crusher, a stirring typefine crusher, a vibration type fine crusher, a swirling air flow typeair classifier, a centrifugal type classifier, and a vibration screentype classifier.

According to this, various fine crushers and classifiers can be used fordispersing the powder, and the powder can be dispersed excellently.

Here, powder disperser 10 may include at least one of an ultrasonicvibrator that ultrasonically vibrates the powder and a voltage applierthat applies a high voltage to the powder.

According to this, at least one of ultrasonic vibration and high voltageapplication can be used for dispersing the powder, and the powder can bedispersed excellently.

According to an aspect of the present disclosure, there is provided apowder coating method for forming coating film using powder having anaverage particle size of 10 μm or less. The powder coating methodincludes: dispersing the powder to remove powder aggregates; and forminga powder layer on the base by directly supplying the dispersed powderonto the base without storing the powder.

According to the powder coating method of the aspect, in the dispersingof the powder, dispersing may be performed using at least one selectedfrom the group consisting of an air flow type fine crusher, a grindingtype fine crusher, a stirring type fine crusher, a vibration type finecrusher, a swirling air flow type air classifier, a centrifugal typeclassifier, and a vibration screen type classifier.

According to the powder coating method of the aspect, in the dispersingof the powder, dispersing may be performed by performing atomizationusing at least one of ultrasonic vibration and high voltage application.

According to the powder coating method of the aspect, in the forming ofthe powder layer, the dispersed powder may be supplied onto the base inan air-dispersed state.

According to the powder layer composite, the coating film, the powdercoating method, and the powder coating apparatus according to thedisclosure, a high-quality coating film can be formed even when fineparticle powder is used.

Above, powder layer composite 100, coating film 51, the powder coatingmethod, and the powder coating apparatus according to the disclosure aredescribed based on the exemplary embodiments and examples, but thepresent disclosure is not limited to these exemplary embodiments andexamples. As long as the gist of the present disclosure is not deviated,various modifications that can be conceived by those skilled in the artare applied to the exemplary embodiments and examples, and the exemplaryembodiments constructed by combining the configuration elements ofdifferent embodiments and examples are also within the scope of thepresent disclosure.

According to powder layer composite 100, coating film 51, the powdercoating method, and the powder coating apparatus of the disclosure,high-quality coating film 51 can be obtained even when the powder havingfine particles is used, and thus, application to the formation of anelectrode layer of a power storage device, such as a condenser, acapacitor, and a battery, is possible.

What is claimed is:
 1. A powder layer composite comprising: a base; anda powder layer having a thickness of 100 μm or less and disposed on thebase, wherein an average of a total value of a number of powderaggregates having a long diameter of 500 μm or greater and a number ofpinholes having a long diameter of 500 μm or greater, in any of aplurality of different regions of 20 mm×20 mm on a surface of the powderlayer, is 0.2 pieces/cm² or less.
 2. The powder layer composite of claim1, an average of a total value of the number of powder aggregates havinga long diameter of 100 μm or greater and 500 μm or less and the numberof pinholes having a long diameter of 100 μm or greater and 500 μm orless, in any of a plurality of different regions of 4.0 mm×6.0 mm on thesurface of the powder layer is 10 pieces/cm² or less.
 3. The powderlayer composite of claim 1, an average of a total value of the number ofpowder aggregates having a long diameter of 50 μm or greater and 100 μmor less and the number of pinholes having a long diameter of 50 μm orgreater and 100 μm or less, in any of a plurality of different regionsof 0.4 mm×0.6 mm on the surface of the powder layer is 10 pieces/cm² orless.
 4. The powder layer composite of claim 1, wherein a concentrationof a solvent contained in the powder layer is 50 ppm or less.
 5. Thepowder layer composite of claim 1, wherein an average particle size ofparticles that form the powder layer is 10 μm or less.
 6. A coatingfilm, wherein the coating film has a thickness of 100 μm or less, thecoating film is provided on a base, and the coating film has a surfaceroughness Ra of 5.0 μm or less.
 7. The coating film of claim 6, whereinwhen a change rate is a value obtained by dividing an original profilevalue, which is obtained by measuring a signal intensity derived from acomposition of the base at a total of 500 points every 10 μm between anytwo points separated by 5.0 mm on a surface of the coating film, by amoving average value of sections at ten points, the change rate iswithin a range of 100±99%.
 8. A powder coating apparatus comprising: apowder disperser that disperses powder; and a powder supplier that isconnected to the powder disperser and supplies the dispersed powderdirectly onto a base without storing the powder.
 9. The powder coatingapparatus of claim 8, wherein the powder disperser includes at least oneof an air flow type fine crusher, a grinding type fine crusher, astirring type fine crusher, a vibration type fine crusher, a swirlingair flow type air classifier, a centrifugal type classifier, and avibration screen type classifier.
 10. The powder coating apparatus ofclaim 8, wherein the powder disperser includes at least one of anultrasonic vibrator that ultrasonically vibrates the powder and avoltage applier that applies a high voltage to the powder.